Princess Anne of England matched a fun orange hat to her suit at the Ascot Racecourse in 2009, the same year Kate paired a matching hat with her lavender coat at the wedding of a British aristocrat. (CREDIT: Samir Hussein/WireImage; Indigo/Getty ) More of Kate Middleton's Style

Princess Charlotte Casiraghi of Monaco looked ready to ride in 2003 at the International Horse Jumping Show. Kate Middleton went for a similar look with tall riding boots and a crisp white skirt in 2007 at the Badminton Horse Trials. (CREDIT: Bruno Bebert/Rex; Rex USA) More of Kate Middleton's Style

Princess Diana dressed in a chic black and white skirt suit at Royal Albert Hall in 1990. Kate dressed similarly to receive her diploma from the University of St. Andrews in 2005. (CREDIT: Tim Graham/Getty; Michael Dunlea/Getty) More of Kate Middleton's Style

Princess Diana wore a feathered hat for an outing in Pembrokshire in 1981, while Kate Middleton wore an almost-identical one to a wedding in 2006. (CREDIT: Jayne Fincher/Getty; Tim Graham/Getty ) More of Kate Middleton's Style

Princess Diana wore a bright red ski jacket for a ski vacation to Klosters in 1986. Kate Middleton wore the same in 2005 for the royal family’s annual ski trip. (CREDIT: Tim Graham/Getty (2)) More of Kate Middleton's Style

Princess Marie Chantal of Greece wore a luxurious fur hat to the wedding of the Dutch Crown Princess in 2002. In 2006, Kate kept warm in a fur hat at the Cheltenham Races. (CREDIT: UK Press/Getty; Tim Graham/Getty) More of Kate Middleton's Style

Princess Diana looked glamorous in a red polka-dot dress at the premiere of 'James Bond For Your Eyes Only' in 1981. Kate Middleton dazzled in the same pattern at the Chakravarty Polo Match in 2006. (CREDIT: Tim Graham/Getty; Rex ) More of Kate Middleton's Style

Princess Diana went shopping at Harvey Nichols in 1995 wearing an understated neutral pant paired with a blazer. Kate Middleton dressed almost identically 10 years later out and about in London. (CREDIT: Rex USA (2)) More of Kate Middleton's Style